1. Field of the Invention
The present invention is concerned with a technology of patterning a resin film or thin metal film on a multilayer thin film such as a FPD (Flat Panel Display). Specifically, the present invention relates to a laser processing device, a laser processing head and a laser processing method for clearing and collecting scattered pieces of a material or debris generated by laser processing in ablation, thermofusion, or interactive effects thereof in which a surface of a material is irradiated with a laser beam.
2. Description of the Related Art
Recent competition in developing and enhancing high-precision flat panel displays (FPDs) with lower cost has been accelerating the manufacture of FPDs with higher qualities and high productivities.
A display panel of the FDP has generally been manufactured by photolithography. In photolithography, however, much attention has been brought on various concerns. For example, devices are likely to have an increased size, and an environmental protection may have to be prepared when using a developing solution or a chemical solution. Further, the photolithography may need two steps in patterning due to the use of different types of resists or developing solutions compared to other types of patterning. In consequence, a technology to directly process a film by laser beams is now widely used in place of photolithography.
An example of the laser used for the aforementioned direct processing includes a short-wavelength laser such as an excimer laser. A typical excimer laser or excited dimmer laser has high photon energy capable of breaking off chemical bonds. The excimer laser can cause ablation of a material, which involves photochemical decomposition or photothermal decomposition, by irradiating a material with a short pulsed laser having a short-wavelength, and can remove or micropattern the material while controlling thermal effects. Such laser processing technology including ablation is currently attracting much attention. Various materials such as plastic (polymeric material), metal, and ceramics can be processed in ablation by irradiating the material with an excimer laser beam having controlled energy density.
In ablation processing using a laser, the material processed usually acquires scattered pieces generated from the surface of the processed material irradiated with a laser beam to the periphery of the processed area. Such scattered pieces of the material are generally called debris. If debris is generated and attached to the periphery of the processing area, neither desired quality nor can desired processing accuracy be obtained. Thus, attempt has been made to study and develop a method of decreasing the debris.
For example, Japanese Unexamined Patent Application Publication No. H10-99978 discloses a device for clearing debris having a fluid delivering device that spouts fluid such as air to the surface around the processed area of a material, and a suction duct located opposite of a fluid spouting outlet that suctions the debris from the processed area of the material (hereinafter called “a first technique”).
Moreover, it is generally known in the art that the amount of debris attached to a material can be decreased if an assist gas is spouted around the laser irradiated area simultaneously when irradiating the material with a laser beam. For example, Japanese Unexamined Patent Application Publication No. H09-192870 discloses a device for clearing debris having a laser processing head including an internal nozzle that spouts an assist gas to the processing area and an external nozzle provided on the outer circumference of the internal nozzle that suctions the spouted gas with the debris. (hereinafter called “a second technique”). It is known in the art that the generation of debris can be prevented by decomposing debris using a prescribed gas. It is also known in the art that the amount of debris accumulated on the material can significantly be reduced by irradiating the material with a laser beam under reduced pressure of vacuum level approximately 10 [Pa] (10−2 Torr).
Japanese Unexamined Patent Application Publication No. 2004-230458 discloses a device for controlling accumulating debris having an opening 120 provided immediately above a processing material 107 stacked on a processing film 108 on a substrate 108a and an exhausting device that decompresses a closed space formed with a mask or variable aperture 104 and an opening 120, where the debris 121 generated by irradiating the material 107 with a laser beam 102 is cleared and the discharged debris 121 is accumulated in the opening 120. As a result, accumulation of the debris on the processing material 107 (hereinafter called “a third technique”) is controlled.